Initially it will only be made available to Dutch customers, says Feike van der Werf, sales director of Siemens SIS, but in time may be deployed more widely. "I see this as the first step in the switch to quantum-based security," says Charlotte Rugers, a security consultant with Siemens SIS.

In essence, this deal means that for the first time QKD will be commercialized and marketed like standard IT services, says Ribordy. Dark fiber has become so prevalent that in some countries you have fiber direct to your home, he says. At the moment it is still not widely used, mainly by organizations that really care about security. But in theory this new deal means that even individuals could adopt the technology, "if you were really paranoid," he says.

This is an important step that should help bring QKD into the mainstream, says Shields. Previously customers were forced to source their own dark fiber, either through laying it themselves or getting a telecom to provide it, but this new deal allows them to buy the complete, scalable package. Although some bigger companies may have their own dark fiber, for smaller companies it would make it easier to adopt the technology, he says. "There are people out there using it but mostly it's to assess the capability, rather than using it to hide their secrets."

It will still be expensive. Besides the $82,000 price tag for a pair of id Quantique's QKD boxes, the cost of dark fiber remains high, because the customer will have to bear the cost of at least two fibers--one for the QKD and the other with which to send the encrypted data once keys have been exchanged. Normally, the cost of each fiber is offset by having dozens of customers share it, says Shields. But QKD customers will be unlikely to want to share their cables. "I think in the longer term we will need to see QKD integrated with normal telecom fibers." But for now this isn't possible, he says. Quantum signals are very weak and classical data signals are very strong, so there is a danger they will be drowned out. Once this problem has been solved, QKD should become even more attractive, he says.